At present, the manufacture of certain elastomeric and polymer latex articles (such as surgical or examination gloves used in hospitals and other medical facilities, work gloves, prophylactics, catheters, balloons, etc.) typically involves two major processes, namely the on-line glove dipping or forming platform process (also known as the primary manufacturing process) and off-line processing (also known as the secondary manufacturing process).
In the dipping or forming platform process, for example, surgical gloves may be formed by one of two methods. One such method is a batch dip process, in which one or more molds (also referred to as formers) are dipped into one or more tanks containing liquid molding material (such as natural latex or synthetic polymers such as polyisoprene, nitrile rubber, vinyl, polyvinylchloride, polychloroprene, or polyurethane) or various other chemicals (such as coagulant). The second method is a continuous dip method, which is the most common, economical, and efficient method for high-volume glove manufacturing.
In a typical continuous dip process, such as that used in the manufacture of surgical gloves, a continuous loop conveyor chain carries the glove molds through the necessary cleaning, dipping, curing, and stripping processes. After a formed glove is stripped from a mold, the conveyor chain carries the mold back to the beginning of the cleaning process to begin a new cycle. Thus, the molds are utilized in a continuous cyclic manner. To increase efficiency, the conveyor chain moves continuously and at a constant speed throughout the continuous dipping process. Specialized equipment is required to conduct the various processes on the gloves as they are constantly traveling through the manufacturing facility. The initial stage of the dipping platform process typically includes the cleaning of the molds, as a clean mold surface is important for forming a quality glove. These clean molds are then carried by the conveyor chain through the coagulant dip process. As the molds continue to traverse laterally along with the conveyor chain, the molds are lowered into, and subsequently raised out of, a coagulant solution contained in an elongated dip tank. After the coagulant dip, the conveyor chain carries the coagulant-coated molds through a second tank containing the liquid molding material, such as latex. The coagulant coatings typically include salts that neutralize the surfactants in the liquid molding material emulsions, and which locally destabilize the liquid molding material, thus causing it to gel (or coalesce) and adhere as a film on the surface of the mold. The molds may be dipped in liquid molding material one or more times to achieve the desired glove thickness. The glove may then be dipped into a leaching tank containing circulating hot water to remove the water-soluble components, such as salts used in the coagulant solution or certain proteins present in the natural latex.
After the glove is formed, it undergoes a drying process in a drying oven to dry the thin gel layer prior to a high-temperature curing process to set and vulcanize the thin gelatinized film onto the mold surface. One or more additional layers, coatings or treatments may be formed or applied to the external surface of the formed glove, either before, after, or between drying and curing. For example, the external layer of the thin film, which typically becomes the user side (also known as the interior or donning side), may be coated with a donning composition or otherwise treated to make donning of the glove easier.
Typically, the final stage of the continuous dipping platform process is the stripping (i.e., removal) of the glove from its mold prior to the mold looping back to the mold cleaning process. Conventionally, the glove removal process is performed by a human operator manually stripping the gloves (with or without the aid of machines) or, in certain cases, using an automated stripping machine to strip the gloves from the molds. This process can result in significant waste if the gloves are not stripped properly. Molded gloves tend to adhere to the surface of the mold, such that the gloves must be gently peeled off of the mold. If they are pulled from the mold too quickly, with too much force, or if they are gripped such that too much stress is concentrated at the gripped points, the gloves can be punctured, torn, or otherwise compromised. Typically, because the cuff edge of the glove is peeled from the mold first, and because the palm and finger areas of the glove adhere to the mold until they are peeled off, the glove becomes inverted or reversed as it is stripped from the mold such that the external surface of the glove after forming (i.e., the donning side) becomes the internal surface after stripping. However, as described below, the donning side typically requires off-line surface treatment alter stripping, so the stripped gloves must be reversed or inverted after stripping to revert the donning side to the exterior surface. Manual and automated inverting processes typically employ suction or bursts of air to assist with fully inverting the glove.
Upon the completion of the on-line dipping process in the dipping platform, the thin film surgical gloves are typically still not finished products. After stripping from the molds, the gloves may undergo several steps of an off-line glove surface treatment process. For example, the gloves may be subjected to an off-line chlorination process, which may involve chlorination, lubrication, and tumble drying prior to inverting the glove such that the donning side becomes the interior surface before the gloves are packaged. These off-line processes often require several pieces of equipment (namely, chemical treatment equipment such as a chlorinator, etc.), an extractor, a tumbling machine, a dryer machine, and/or miscellaneous supporting equipment. Additionally, the off-line equipment is configured to process the gloves in batches, which requires that the formed gloves coming off of the dipping process line be temporarily stored in a queue, which consumes time and physical storage space, to wait for the batch processing equipment to become available. processes are substantial manual operation may also be necessary to operate these pieces of equipment, load and unload the gloves, transfer the gloves and complete these off-line processes prior to packaging the surgical gloves as finished products.